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Finding the Fourth Proportional to 670.55, 925.40 and 421.78

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Solution

The fourth proportional to 670.55, 925.40 and 421.78 is: 582.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    670.55 : 925.40 = 421.78 : x
  2. Step 2: Convert to fraction form
    670.55/925.40 = 421.78/x
  3. Step 3: Cross multiply
    670.55x = 925.40 × 421.78
  4. Step 4: Simplify right side
    670.55x = 390,315.21
  5. Step 5: Solve for x
    x = 390,315.21/670.55
  6. Step 6: Final answer
    x = 582.08

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.